Women who make healthy lifestyle choices lower their risk of developing invasive breast cancer, regardless of whether they have a family history of the disease, according to a new study.

"We have more awareness of our familial risks, and we may be led to believe there's nothing we can do — that it's fate," said study researcher Dr. Robert Gramling, a professor at the University of Rochester in New York. But his study showed "whether or not you have a family history of the disease, engaging in healthy behaviors is beneficial."

Women with a family history of breast cancer had a higher risk than those without, he said, but both groups lowered their risk by a similar proportion by maintaining a healthy lifestyle.

Specifically, the researchers found women who had a family history of breast cancer lowered their risk by about one-fourth by getting regular exercise, limiting their alcohol intake and maintaining a healthy body weight.

Similarly, women without a family history of the disease who followed a healthy lifestyle lowered their risk by about the same amount, Gramiling said.

The researchers based their analysis on data from 85,644 postmenopausal women who participated in the Women's Health Initiative, a long-term study launched in 1991 and conducted by the National Institutes of Health. They considered a woman to have a family history of breast cancer if her mother or sister developed the disease after age 45.

Gramling was surprised, he said, that the findings in the two groups were nearly the same.

"It would have been expected that women without a family history of the disease would have lowered their risk," with a healthy lifestyle, he said. That women with a family history of breast cancer lowered their risk by a nearly-identical amount was more unexpected, he said.

In his medical practice, Gramling told MyHealthNewsDaily, he's encountered women who seem to have come to believe there's nothing they can do to lower their risk, but these results show otherwise.

Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

The researchers defined regular exercise as 20 minutes of moderate or vigorous activity at least five times a week, moderate drinking as fewer than seven drinks per week and a healthy body weight as having a body mass index or BMI (a measure of a person's weight in proportion to her height) between 18.5 and 24.9.

The researchers chose to include exercise, BMI and alcohol intake in their definition of a healthy lifestyle, Gramiling said, as opposed to other factors such as eating lots of fruits and vegetables, because these criteria have shown the strongest evidence, based on previous studies, of having an impact on one's breast cancer risk.

"Many of us have some family history of a scary disease," Gramling said, "this shouldn't be a barrier to making healthy choices."

The analysis excluded women who had previously had breast cancer, as well as those with a mother or sister who had developed early-onset breast cancer (before age 45), because it was more likely such women have genetic factors that may put them at an even higher risk.

The study is published today (Oct. 12) in the journal Breast Cancer Research.